In recent years, processing of electronic data has increased continuously. With the processing of the data also the exchange of the data has increased. This is also true for data that have to be protected against unauthorized reading or writing of the data. For this, encryption systems have been developed that are widespread, for example, public key encryption systems.
Private data are data that an owner of the private data does not want to share with a further party. Such private data may for example be legally protected because they may belong to a protected privacy area of a person. In a further example, such private data may also be business data that are confidential.
Sorting private values of different parties involves comparing the private values and conserve privacy of the private values. Yao's millionaires' problem involves a comparison of private data between two parties. In an article with title “Protocols for Secure Computations” for the Proceedings of the annual IEEE Symposium on Foundations of Computer Science 23, 1982, A. Yao defined the millionaires' problem: two millionaires want compare an amount of money that each one has without revealing the amount of money to each other. A plurality of solutions has been suggested to Yao's millionaires' problem some of which involve a third party. Such a third party has to be found by the two millionaires and may not be available. Two-party solutions involve only the two parties that own the two private values that are desired to be compared. Solutions of Yao's millionaires' problem may be used as a building block for sorting of private values from more than two parties. However, solutions of Yao's millionaires' problem require an amount of computational resources that may be high and using the solutions as the building block for sorting may be inefficient for more than two parties.